From a doctor too:
Nearly 80% of people diagnosed with lung cancer now, in 2012, are non-smokers. All of the anti-smoking campaigns imaginable are not going to make a difference for this 80%.
Maybe a few numbers will make it even clearer. In 2008, the last year from which we have numbers available, there were 158,592 deaths from lung cancer in the United States, including 70,051 deaths in women. (Note that in the same year, there were 40,589 breast cancer deaths in women.) Using the 80% statistic, 126,874 of these deaths could not have been prevented by anti-smoking campaigns.
Perhaps we need to start looking at how we diagnose earlier and treat better rather than incanting the magic words "stop smoking, stop smoking"?
Update: It isn't. of course, quite that simple - here's a little challenge to the good doctor's argument (lifted from the comments below)